what speed should OD engage?
I have an 05 Explorer 4.0L 2WD which at about 48 mph the OD kicks in and RPMs drop to about 1500. When this happens a moaning sound can be heard from the front of the vehicle, espcially if I acclerate. Sometimes a faint rattling noise can be heard also. Sometimes it will stay in OD and not downshift with moderate acceleration Is this normal?